Eh, I didn't find it so surprising. There was talk of something like this for a long time anyway because

Spoiler :

they never did really talk too much about his mother, leaving her part in any of this as a mystery. Plus, Quincies are technically still human, so it's not like Kubo violated his own canon here. And trying to explain the backstory behind his parents meeting and why Ryuken and Isshin know each other. Long-standing loose ends that could be tied up quite nicely by this.

I think it's pretty much a given that Ichigo is going to be every single different race that appears in the series. A singularity, if you will.